Positive engagement indicator for wireline fishing operations

Abstract

A device and method for retrieving a tool string from downhole locations through the use of one or more engagement sensors. The one or more engagement sensors are activated by the tool string engaging an overshot device. The one or more engagement sensor may be mechanical, electric, or magnetic and may be located at various locations on the overshot device, the tool string, or both. Additionally, any number of engagement sensors may be used at the same time.

Description

BACKGROUND OF THE INVENTION[0001]The present disclosure relates to the field of borehole drilling for the production of hydrocarbons from subsurface formations. In particular, the present disclosure relates to fishing operations to recover tool strings.[0002]An example of a fishing operation is the retrieval of a logging tool string that is stuck in a well. Logging tools may become stuck due to encounters with bridges, cave-ins, swelling formations, debris and the like. Often, an overshot device is used to enage the stuck tool string. During fishing operations, it is common practice to circulate mud or other substances down onto the stuck tools to clean the top of the fish that protrudes from the cable head of the tool string, and to determine when the overshot assembly engages the tool string. Typically, when the pump pressure increases, it is assumed that the pressure increase is due to the logging string being swallowed up by the fishing equipment overshot device. Currently, reco...

AI Technical Summary

Benefits of technology

Ensures safe and reliable engagement of tool strings, reducing the likelihood of drops during retrieval, prolonging tool life by minimizing tension and allowing for safer circulation practices, and eliminating the need for pump-out subs, thereby enhancing operational efficiency and safety.

Problems solved by technology

Logging tools may become stuck due to encounters with bridges, cave-ins, swelling formations, debris and the like.

It is important that the logging operation continue because the logging operation cost is based largely on the rig operation which is charged on an hourly basis and is generally quite expensive.

Recovery of the tool reduces but does not eliminate the possibility that the tool string is dropped when the drill pipe is retrieved to the surface.

The problem with the current state of affairs is that the tension increase that is seen by the logging engineer is only an indication that the drill string is pushing on the tool string.

The tension increase is not, however, a complete indication that the overshot has actually swallowed the instrument itself or that the tool string is being engaged by the grapple within the overshot device.

Instead, the tension increase could be the result of debris or other matter within the borehole itself that is preventing the instrument from being completely grappled by the overshot device.

Unfortunately, dropping the tool string is a familiar occurrence during fishing operations.

Moreover, once the tool string is engaged, circulation is generally impossible or only possible when a pump out sub is run for the express purpose of providing circulation after the fish is engaged.

In many cases it is not recommended to circulate because the possibility exists that the fishing neck of the tool string is not properly engaged and the circulation can push the tool string out of the fishing equipment and be lost once again downhole.

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